Relations R1, R2, R3 and R4 are defined on a set A = {a, b, c} as follows : R1 = {(a, a) (a, b) (a, c) (b, b) (b, c), (c, a) (c, b) (c, c)} R2 = {(a, a)} R3 = {(b, a)} R4 = {(a, b) (b, c) (c, a)} Find whether or not each of the relations R1, R2, R3, R4 on A is (i) reflexive (ii) symmetric (iii) transitive